Polymarket Gamma API: Markets, Events & Token IDs (2026)

API · Reference

The Gamma API at gamma-api.polymarket.com is the "catalog" - it's how you discover markets and events and get the token IDs the CLOB needs to trade. It's public, no auth, so you can explore every endpoint from a browser or curl right now, and so can the live tools on this page.

The endpoints you'll actually use

Common query parameters on /markets and /events: active=true, closed=false, slug=, tag_slug=, order=volume24hr, ascending=false, limit= and offset= for paging.

GET /markets - request and response

Ask for one market by slug. You get back an array (even for a single market), so take element [0]:

curl -s "https://gamma-api.polymarket.com/markets?slug=will-it-rain-in-nyc-today" | jq '.[0]'

import requests, json
m = requests.get("https://gamma-api.polymarket.com/markets",
                 params={"slug": "will-it-rain-in-nyc-today"}).json()[0]

A trimmed, annotated response (the fields a bot cares about):

{
  "id": "519284",
  "question": "Will it rain in NYC today?",
  "slug": "will-it-rain-in-nyc-today",
  "conditionId": "0x1f2e...c0",      // the market id (NOT what you trade on)
  "active": true,                    // listed and live
  "closed": false,                   // not yet resolved
  "acceptingOrders": true,           // the CLOB is currently taking orders
  "outcomes": "[\"Yes\", \"No\"]",          // JSON string -> parse it
  "clobTokenIds": "[\"7142...\", \"1098...\"]", // JSON string, aligned with outcomes
  "outcomePrices": "[\"0.62\", \"0.38\"]",     // JSON string, last prices
  "bestBid": 0.61,
  "bestAsk": 0.63,
  "lastTradePrice": 0.62,
  "volume24hr": 48213.5,
  "endDate": "2026-06-16T00:00:00Z"
}

The two outcome token IDs live inside clobTokenIds. They are what the CLOB trades on - read them and you can place an order.

The #1 gotcha: JSON-encoded string fields

Gamma returns clobTokenIds, outcomes and outcomePrices as JSON-encoded strings inside the JSON, so you have to decode them a second time. And never hardcode which token is "Yes": read the parsed outcomes array and map by name, because the order is not guaranteed.

import requests, json
m = requests.get("https://gamma-api.polymarket.com/markets",
                 params={"slug": SLUG}).json()[0]
outcomes   = json.loads(m["outcomes"])        # e.g. ["Yes", "No"]
token_ids  = json.loads(m["clobTokenIds"])    # aligned with outcomes
prices     = json.loads(m["outcomePrices"])   # aligned with outcomes
yes_token  = token_ids[outcomes.index("Yes")]
print(yes_token, prices[outcomes.index("Yes")])

const r = await fetch(`https://gamma-api.polymarket.com/markets?slug=${SLUG}`);
const m = (await r.json())[0];
const outcomes  = JSON.parse(m.outcomes);
const tokenIds  = JSON.parse(m.clobTokenIds);
const yesToken  = tokenIds[outcomes.indexOf("Yes")];

curl -s "https://gamma-api.polymarket.com/markets?slug=$SLUG" | jq -r '.[0].clobTokenIds | fromjson | .[0]'

Try it on a real market - paste a slug and pull its token IDs live:

Scan for tradeable markets

A typical bot's discovery query asks for active, open markets, busiest first, in one category:

GET https://gamma-api.polymarket.com/markets
    ?active=true&closed=false&order=volume24hr&ascending=false&limit=20&tag_slug=politics

Filter the result client-side to markets that are genuinely tradeable before you act on them:

# keep only markets the CLOB will accept orders on right now
tradeable = [m for m in markets
             if m.get("active") and not m.get("closed") and m.get("acceptingOrders")]

Search live (this calls /public-search, then loads token IDs per market):

Paging and freshness

• Paging: add limit and offset and walk until you get a short page. Keep limit ≤ 500 on /events, ≤ 300 on /markets.
• Freshness: prices (bestBid, bestAsk, lastTradePrice) move constantly. Gamma is fine for discovery and a rough price, but quote and trade off the live CLOB book, not a cached Gamma price.
• Caching: cache the slug -> token_id mapping (it's stable), not the prices.

GET /events - multi-outcome groups

An event bundles related markets (e.g. "NYC Mayoral Election" holds one market per candidate). Use it to render multi-outcome cards or to find every market on a topic:

curl -s "https://gamma-api.polymarket.com/events?slug=nyc-mayor-2025" | jq '.[0].markets | length'

Each event has a markets array; every entry has the same clobTokenIds / outcomes string fields as a top-level market, so the same parsing applies.

Field reference (the ones that bite)

Next: CLOB API (trade on a token_id) · Data API (history & PnL) · Fix an error.